The present invention relates to improvements in insulated glass door and window structures and more particularly relates to an apparatus and method for eliminating or reducing condensation on the external face of such glass doors and the internal face of window structures. More particularly the present invention relates to improvements in the structure of insulated glass door/window structures such as are used in connection with insulated glazed windows (for use in both thermal and sound insulation applications) and refrigeration, and particularly in industrial and commercial refrigeration. The invention also relates to improvements in the economics of manufacture of insulated glass doors and windows. Although the invention will primarily be described with reference to its application in glass doors and particularly triple glazed doors used in such applications as refrigeration, it will be appreciated by persons skilled in the art that the invention has applications in other areas such as in windows and any structure which utilizes glass and particularly though not exclusively double or triple glazing.